1. Field of the Invention
The present invention relates to a method for analyzing contamination within a hole in semiconductor device suitable for analyzing metal contamination within a fine hole formed on a semiconductor substrate.
2. Description of the Related Art
Associating with integration of semiconductor device, contact hole and through hole are down-sized and an aspect ratio is progressively increasing. In 1 Gbit dynamic semiconductor random access memory device (1 Gbit DRAM), it has been considered to be required hole having aspect ratio of 5 to 10 at an opening diameter of 0.15 .mu.m of the contact hole and the through hole. It is important technology for improving reliability of the device, to wash out metallic contaminant presenting within the fine hole and having high aspect ratio.
In order to develop a new washing liquid which can wash out metallic contaminant in fine hole, it is required to judge whether the metallic contaminant within the hole could be satisfactorily removed utilizing a typically used acid washing liquid, such as sulfonic hydrogen peroxide solution or the like and what extent a new washing liquid to be used in combination with surface active agent is effective. Therefore, technology for analyzing metal contamination amount within the hole is important for developing new washing liquid.
Currently, as a technology for making analysis of metallic contaminant amount, an atomic absorption method, an inductively coupled plasma (ICP) mass analyzing method and a X-ray fluorescence total reflection analyzing method are employed. All of these methods are technology for analyzing metallic contaminant amount presenting on the surface of the semiconductor layer. Among these methods, atomic absorption method permits measurement of metallic contaminant amount presenting on the surface of the semiconductor substrate by dissolving natural oxide layer on the surface of the semiconductor substrate by HF vapor or the like, collecting the solution, and analyzing metallic contaminant amount in the solution by atomic absorption measurement device. Similarly, ICP mass analyzing method makes analysis of the metallic contaminant amount in the collected solution by ICP mass.
Such atomic absorption method and ICP mass method can analyze metallic contaminant amount depositing on the semiconductor substrate having no irregularity. However, it is not possible to analyze contaminant amount residing within the hole.
On the other hand, XPS method and atomic spectrum analysis (AES) method irradiating a beam of X ray or the like in the fine region of the surface of the semiconductor substrate are low in detection sensitivity with respect to contaminant and cannot detect contamination unless the surface contaminant concentration is greater than or equal to 10.sup.14 atoms/cm.sup.2.
In the current semiconductor cleaning technology, contaminant concentration less than or equal to 10.sup.10 atoms/cm.sup.2 is required. Accordingly, it has been required a method for measuring contamination in the fine hole at high sensitivity and preparation method of a sample for analysis.